Conventional door drives include at least one regulating valve for the adjustable regulation of a fluid flow within the door drive. Generally, the fluid to be regulated is hydraulic oil. Hereby, the regulating valve regulates the fluid flow, for example in that the regulating valve affects the cross-sectional surface of a fluid channel at least at one portion of the fluid channel. Typical fields of application are dampening functions for dampening the movement of the door leaf, which is in operative connection with the door drive.
Usually, the setting of the regulating valves of a door drive is effected in the final mounting position, i. e. when the door drive is operatively connected to the door. This is required, because, on account of the multiplicity of different doors with correspondingly different features, a preliminary adjustment of the regulating valve is not reasonable. From the point of view of production techniques, an adaptation of the door drive to a specific door variant is not desired, because it is considerably less expensive to produce the least possible number of variants of one door drive. Furthermore, it may be required that the regulation of the fluid flow needs to be readjusted after a certain period of time. This circumstance results in the fact that the regulating valve will have to be accessible for an operator in the mounting position for adjusting the regulation. With the intention to protect the regulating valves from being damaged by inappropriate manipulation, in particular the engaging parts of the regulating valves are manufactured from robust materials, such as metal.
Door drives pertaining to the group of overhead door closers, the housing thereof may be mounted to both the door leaf and the door frame, to the door casing or to the wall, in which the door is recessed. Furthermore, it is distinguished between mounting to the pull-side or the push-side, as well as the mounting to DIN-left-handed doors or DIN-right-handed doors.
One group of conventional door drives is disadvantageous in that for covering all possible combinations of the above described mounting variants at least two variants of the door drive need to be manufactured, because only one variant will not guarantee that in each case the regulating valves are accessible to an operator for adjusting the regulation. Alternative conventional door drives use only one variant of the door drive for covering all potential combinations of the above described mounting variants, however, they do have restricted functionality. These door drives are in particular not functioning over a door opening angle of at least 180°, because these door drives need to employ a symmetric cam disk, instead of an asymmetric cam disk, for being able to reduced the number of variants from two to one.
Another group of conventional door drives bypasses the disadvantage of imposed multiplicity of variants in that two regulating valves are provided for each regulation of a fluid flow in these door drives, wherein in the mounting position at least one of the regulating valves is accessible for an operator for adjusting the regulation. However, this circumstance is disadvantageous in that the increased number of components increases the cost of the door drive and the reliability of the door drive decreases. Furthermore, additional construction space is necessary in the door drive for the additional regulating valves and the additional hydraulic channels. Furthermore, prior to mounting, the regulating valves, which are no longer accessible in the mounting position, need to be completely closed, so as to allow for being able to adjust the regulation of the fluid flows within the door drive in the mounting position with the accessible regulating valves. Hereby, it is particularly problematic, if, in the mounting position, it becomes clear that a no longer accessible regulating valve is not closed. In this case, the regulation of the corresponding fluid flow is only possible in a restricted way or not at all, unless the door drive will be dismounted from the mounting position thereof and the not closed regulating valve will be subsequently closed.